Do task and item difficulty affect overestimation of one’s hand hygiene compliance? A cross-sectional survey of physicians and nurses in surgical clinics of six hospitals in Germany

Background One barrier to hand hygiene compliance is overestimation of one’s own performance. Overconfidence research shows that overestimation tends to be higher for difficult tasks, which suggests that the magnitude of overestimation also depends on how it is assessed. Thus, we tested the hypothesis that overestimation was stronger for hand hygiene indications with low compliance (i.e., high difficulty), and the hypothesis that self-reported overall compliance based on a single item is higher than based on “5 Moments of Hand Hygiene” (WHO-5) items, since the single item implies an aggregation across indications. Methods In the WACH trial (German Clinical Trials Register [DRKS] ID: DRKS00015502), a questionnaire survey was conducted among physicians and nurses in nine surgical clinics (general/visceral surgery or orthopedics/trauma surgery) of six German hospitals. Self-reported compliance was assessed both by a single item and the WHO-5-items using percentage scales. These were compared with each other and with direct observations. Relative frequencies of the WHO-5 indications used to calculate the WHO-5-based self-reported overall compliance rate were estimated by a systematized review of the literature (see appendix). In analysis, t-tests, Chi2-tests and multiple linear regressions were used. Results Ninety-three physicians (response rate: 28.4%) and 225 nurses (30.4%) participated. Significant compliance differences between physicians and nurses were found for direct observations and were in favor of nurses, while no such differences were found for self-reports. Across the WHO-5, overestimation showed inverse correlations with observed compliance (physicians: r = −0.88, p = 0.049; nurses: r = −0.81, p = 0.093). Support for the hypothesis that the self-reported overall compliance based on one item is higher than that based on WHO-5 items was found for physicians (M = 87.2 vs. 84.1%, p = 0.041; nurses: 84.4 vs. 85.5%, p = 0.296). Exploratory analyses showed that this effect was confined to orthopedic/trauma surgeons (89.9 vs. 81.7%, p = 0.006). Conclusion Among physicians, results indicate stronger hand hygiene overestimation for low-compliance indications, and when measurements are based on a single item versus the five WHO-5 items. For practice, results contribute to infection prevention and control’s understanding of overestimation as a psychological mechanism that is relevant to professional hand hygiene. Supplementary Information The online version contains supplementary material available at 10.1186/s13756-022-01188-7.

of the mean frequency distribution of these indications may be used as a denominator in calculating compliance rates when only the numerator, i.e., the number of disinfections, is known, or as weights for calculating overall compliance when only WHO-5-specific compliance rates are available.

Objective
To provide an estimate of the mean frequency distribution of hand hygiene opportunities by indications  in highly developed countries.

Eligibility criteria
The inclusion criteria were:  original study;  conducted in one or more highly developed countries (human development index [HDI]) >= 0.75);  explicit use of the concept of hand hygiene opportunities;  reporting the absolute or relative frequencies of hand hygiene opportunities for all  indications (before patient contact, before an aseptic task, after body fluid exposure, after patient contact, and after contact with patient surroundings);  use of direct observation (Sax et al., 2009;WHO, 2009), video or electronic observation.
Studies that distinguished more than the five indications were excluded.

Search strategy
"Hand hygiene opportunities" was searched, using neither quotation marks nor filters or limits.

Selection process
Only one reviewer (first author) screened the records (thus rendering this review to qualify as a systematized review; Grant & Booth, 2009;Sutton et al., 2019). No automation tools were used.
Titles and abstracts were screened based on the inclusion and exclusion criteria. If an abstract clearly indicated that no absolute or relative frequencies of hand hygiene opportunities in terms of the WHO-5 indications were reported in the study, the record was excluded. Additionally, studies conducted from countries with an HDI < 0.75 were also excluded.

Data collection process
Only one reviewer (first author) collected data from the included studies (reflecting the systematized review classification). Only data on absolute or relative frequencies of hand doi: 10.1186/s13756-022-01188-7 III hygiene opportunities in terms of the WHO-5 indications were extracted. No data were obtained or confirmed through communication with study investigators, and no automation tools were used in the process.

Data items
Data on the absolute or relative frequencies of hand hygiene opportunities in terms of the WHO-5 indications were sought. If studies reported such data for different points in time or contexts (e.g., before and after an intervention, or in different wards), the opportunities were summed. If studies reported the overall number of observed opportunities together with the distribution of the WHO-5 as percentages, the absolute numbers of opportunities per WHO-5 indication were calculated by multiplying the overall number with these percentages to obtain the number per indication.

Study risk of bias assessment
The study settings, designs, and methods employed for hand hygiene observations (direct or video observation) were coded. Due to the austere objective of determining the empirical distribution of hand hygiene opportunities across the WHO-5, systematic assessment of risk of bias was not conducted.

Effect measures
The relative frequencies of hand hygiene opportunities classified according to the WHO-5 indications were averaged. In doing so, each study was weighted equally, since weighting by study size (i.e., by the number of hand hygiene opportunities observed) would have introduced a bias in that size does reflect the resources available for the studies rather than real-world proportions of the numbers of opportunities.

Synthesis methods
Only one tabular synthesis was conducted, and all included studies were eligible. No methods for handling missing summary statistics or data conversions were used. The methods used to tabulate the results of individual studies and syntheses were confined to the calculation of simple absolute and relative frequencies. The heterogeneity of the study results was described by providing 95% confidence intervals. Neither methods to explore causes of heterogeneity nor sensitivity analyses were used.

Reporting bias assessment
No methods were used to assess the risk of bias due to missing results in the synthesis arising from reporting biases.

Certainty assessment
No methods to assess certainty or confidence in the body of evidence for the outcome were used. Figure A1 shows the study selection process. Reports were not sought. Of the initial 529 records, no study was removed before screening, and 454 studies were excluded after screening. Of the 75 remaining studies, 39 reported no distribution of WHO-5 hand hygiene opportunities, 10 were from countries with an HDI < 0.75, two reported fewer than five hand hygiene indications (Goodliffe et al., 2014;Muller et al., 2015), and one study more than five

Study selection
indications .

Study characteristics
The included studies were conducted in 13 countries (USA 6 studies, Germany 5, Australia 3,

Risk of bias in studies
Twenty of the studies were cross-sectional observational studies; one study had a beforeafter design, one was a quasi-experimental interventional study, and one was a clusterrandomized control trial, Additionally, 20 studies used direct hand hygiene observations, two studies used video recording, and one study used electronic technology. In accordance with section 11., no systematic assessments of risk of bias are reported.

Results of synthesis
The mean percentages of the indications "before patient contact", "before an aseptic task", "after body fluid exposure", "after patient contact", and "after contact with patient surroundings" were 30.0% (95%

Reporting biases
In accordance with section 13., no assessments of risk of bias due to missing results in the synthesis arising from reporting biases are presented.

Certainty of evidence
In accordance with section 15., no assessments of certainty or confidence in the body of evidence for the outcome are presented.

Discussion
This review has limitations. First, it represents not a systematic, but a systematized review (Grant & Booth, 2009;Sutton et al., 2019) in that because it was performed as a doctoral student assignment, there was only one reviewer (first author), and only one database was used (PubMed). Second, it did not differentiate between professional groups, e.g. physicians, nurses, and allied health professionals.
Third, medical specialties were not contrasted. Nonetheless, this review represents, to our knowledge, the first quantitative review of the distribution of hand hygiene opportunities across the indications defined by the WHO (WHO-5). Despite considerable variation in the studies' sizes and contexts, it provides plausible and quite robust estimates of the average relative frequencies of the WHO-5. These estimates were usable as weights for the self-reported WHO-5-specific compliance rates in the study to which this review is appended. Further research should elucidate whether the estimates can be used as denominators in cases in which such data are missing, and more generally whether there are of value in increasing the construct validity of hand hygiene assessments (Neo, 2017).

Registration and protocol
Because this review was conducted in the context of a doctoral student assignment to provide weights for the WHO-5 indications in the context of the analyses conducted in the above manuscript, no review protocol was prepared and no registration to a registry has been filed.

Support
The review received no financial or nonfinancial support, and no funders or sponsors had any role in the review.

Competing interests
The authors declare no competing interests.

Availability of data, code, and other materials
The data analyzed in this review are available from the corresponding author upon reasonable request.